The Arizona sentinel., 1887-03-26

faster-spreading species would get as far as Ireland; others, not so quick, would only get to England; while some would not have time to get even as far And so, when the continuity of land was broken up, Ireland had received fewer than England, and England itself only a portion of the continental species; and itmay be that Ireland was separated from England before the lat ter was severed from the continent. The smaller native flora of Ireland is ac- counted for by the same facts.
 Geology is no respecter of nations. Not only does it show us our proud island as mere fragment of the conti- nent, but we are also assured that some of our chief rivers were only tributaries of the Rhine. We fear that some patriotic politicians will have a quarrel with geology on this point During portion of the glacial period, the land was covered, or nearly so, by the sea, and afterwards united by the continent, chiefly by a plain of powder clay. Through this plain Prof Ram sey thinks the Rhine wandered to its mouth in the north part of the North sea; while the Thames, the Tyne, the rivers of the Wash and Humber, and possibly some Scottish rivers, were its tributaries. Thus the solid lands and the constant rivers are shown to be mere passing phases in an ever-chang- ing picture.
 The political geography of Europe has undergone great changes in his toric times; geology tells of extensive physical changes in the more distant past. The outlines of physical geog- raphy very different from that of to-day have been sketched out for us in the caves and on the rocks. Geologists have transferred the sketch to paper in the ordinary style of map-drawing Here is an outline of it: The Bristol channel is fertile valley, where the horse, bison, elk, mammoth and rhi- noceros browse on the rich herbage. Lions, wolves and other beasts of prey pursue and devour them, where now the salt waves roll. The British Isles are united to the continent, and the Rhine flows along a great valley, now the North sea, and is joined by its tributaries. the Elbe, Thames. etc. Extensive valleys occupy the sites of the English and St. Georges channels, where the herbivora graze, and are pursued by their carnivOrOus contemporaries. Spain, and Italy with Sicily, being respectively joined to Africa, divide the Mediterranean into two large lakes; Corsica and Sardinia united form a great promontory, stretching out into the most western of these. Across these connecting areas the animals of Africa-the lion. spotted hyena, Kafir cat, serval, antelope and African elephant-pass into Europe. After long ages their remains are found in the caves, to testify of this former state of things. Geology receives aid from every other science, and in return throws back light upon each. Meteorology, or the science of the weather, is one on which geology largely depends; it furnishes the key note for the resolution of many geologic al problems. In return, geology has enriched it with many interesting facts with regard to the weather of the ages that are gone. Rain-prints and ripple marks on slabs of sandstone or shale tell us that the rain fell, and that the wind ruffied the surface of the water. Rounded fragments and striated peb- bles tell us of rivers rolling along their gravel, and glaciers moving down the valleys. Such evidence is so common and well known, that it ceases to surprise us. When, however, we hear that there is good geological evidence to show that in times so remote as the Silurian, the prevailing winds in this region were westerly, as they are to-day, our wonder can no longer be restrained. Evidence of the prevailing westerly winds in the present is seen in the one sided growth of trees towards the east in exposed situations. The growth of large towns towards the west, to avoid the smoke from the manufacturing quarters, is another proof And what is the witness of the rocks to a similar prevalence in the past? Long ago, when the rocks which we call Silurian were being laid down, Wales was a center of volcanic activity. Mount Snowdon is formed of the products of the volcanoes of the period, interstratiied with contempo- raneous sedimentary rocks. The roots of some of these old volcanoes have been found and examined. The ash beds around them thin out very rapidly | toward the west, while to the east and north they are much thicker. Toward the east they thicken for a space, and then thin out. It is evident that the greater part of the lighter volcanic products fell to the east of the mount aims. The natural explanation is, that the wind blew more strongly and frequently from the west and southwest than from other quarters,
 Geology teaches us that countless forms of life have passed away, as far as we can tell. forever:
 From scarped cliff and quarried stone,
 She cries, thousand types are gone
 Species and genera which once had a local habitation on earth have disap- peared from the stage, and have now only a name; and not only species and l penera but whole orders have come